A low-depth lateral flow aerobic granular sludge treatment device and a method for changing a four-corridor carousel oxidation ditch into a continuous flow aerobic granular sludge

Abstract

The present application relates to water treatment device technical field, specifically provide four corridor carousel oxidation ditch is changed into continuous flow aerobic granular sludge method, including the following steps: flow state reconstruction, aeration system reconstruction, water distribution backflow system, granular sludge cultivation system construction. Beneficial effect lies in, realizes the low depth pool application aerobic granular sludge technology, the removal efficiency of pollutants is significantly improved, shortens the granular sludge formation cycle, guarantees the stability of granular sludge, the transformation cost is low, and energy consumption is less.

Description

Technical Field

[0001] This invention relates to the field of water treatment equipment technology, specifically a low-depth lateral flow aerobic granular sludge treatment device and a method for converting a four-corridor Carrousel oxidation ditch into a continuous flow aerobic granular sludge treatment device. Background Technology

[0002] With increasing environmental awareness and increasingly stringent environmental regulations, countries are continuously raising the requirements for effluent quality from wastewater treatment plants, especially regarding the removal of nutrients such as nitrogen and phosphorus. Traditional wastewater treatment processes are facing severe challenges in upgrading. How to upgrade existing wastewater treatment facilities at low cost to meet the latest environmental requirements is a pressing issue that urgently needs to be addressed.

[0003] The Carrousel oxidation ditch is a widely used modified activated sludge process. It is essentially an extended aeration system that uses circulating water in a ring-shaped ditch to degrade organic matter and remove nitrogen and phosphorus.

[0004] The characteristics of the Carrousel oxidation ditch are as follows: 1. The effective water depth is shallow (usually 2.5~4m), the reaction rate is slow, and the land area required for the same treatment scale is large; the ring ditch design has high requirements for the site shape, the space utilization rate of the pool is low, and a large amount of land needs to be acquired for new treatment scale.

[0005] 2. Surface aeration / inverted umbrella aeration equipment is prone to wear and tear and has a high failure rate. Underwater mixing equipment is prone to sludge entanglement, requires frequent maintenance, and has high maintenance costs. The average service life of the equipment is 8 to 10 years.

[0006] 3. Suitable for wastewater treatment plants with stable influent water quality and low discharge requirements (such as rural wastewater and low-standard municipal wastewater), projects with sufficient site and low sensitivity to energy consumption and sludge disposal costs.

[0007] Upgrading the Carrousel oxidation ditch directly requires the addition of denitrification filters, advanced treatment units, etc., which involves a large amount of work and a long period of time.

[0008] Continuous flow aerobic granular sludge process is a rapidly developing new biological treatment technology in the field of wastewater treatment. Due to its unique granular structure and internal microenvironment differences, aerobic granular sludge has a strong resistance to shock loads and can efficiently remove pollutants such as organic matter, nitrogen, and phosphorus within a short hydraulic retention time. It can also maintain stable treatment effects under fluctuating water quality conditions, making it an ideal alternative to solve the shortcomings of traditional processes.

[0009] However, the common effective water depth of this process is 4 to 6 meters. Modifying it under shallow pool conditions such as the Carrousel oxidation ditch presents many technical challenges. At the same time, the formation of aerobic granular sludge requires a suitable organic load, necessary hydraulic shear force, and a rich microbial community. How to meet the above conditions on the basis of the original structure of the oxidation ditch has become the key to process modification.

[0010] Based on this, the present invention provides a low-depth lateral flow aerobic granular sludge treatment device and a method for converting a four-corridor Carrousel oxidation ditch into a continuous flow aerobic granular sludge treatment device, in order to solve the difficult problems of upgrading and transforming the Carrousel oxidation ditch. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide a low-depth lateral flow aerobic granular sludge treatment device and a method for converting a four-corridor Carrousel oxidation ditch into a continuous flow aerobic granular sludge treatment device. This solves the problems of high cost of upgrading and modifying Carrousel oxidation ditches and insufficient pool depth in the prior art, which makes it difficult to utilize existing aerobic granular sludge devices.

[0012] This invention discloses a method for converting a four-channel Carrousel oxidation ditch into a continuous flow aerobic granular sludge treatment, comprising the following steps: S1, Flow Modification Install partition walls within the Carrousel oxidation ditch to break the original circular flow pattern of the ditch and transform it into a lateral flow pattern; S2, Aeration System Modification The original inverted umbrella aeration or surface aeration methods have been abandoned and replaced with an adjustable blower bottom aeration system; S3, Water Distribution and Return System The water distribution and return system is built at the common wall of the Carrousel oxidation ditch I and II, and is equipped with a water distribution channel and a return channel. The water distribution channel is equipped with one or more rows of water distribution holes, or is replaced with water distribution pipes with small holes. Wastewater is evenly distributed to the entire tank through the water distribution pipes, avoiding sludge deposition caused by excessively low local water flow velocity and achieving uniform distribution of influent load. The return channel serves as a channel for sludge return, realizing the directional circulation of granular sludge from subsequent units to the anaerobic zone. S4. Construction of granular sludge cultivation system An aerobic granular sludge generator is built into the second microaerobic aeration zone. This generator has the dual functions of granular sludge cultivation and sludge-water separation, providing a suitable growth environment for microbial self-flocculation to form granular sludge. An air-lift device is connected to the sludge hopper of the aerobic granular sludge generator. The air-lift device is connected to the return channel, replacing the traditional pump return method. The sludge at the bottom of the generator is lifted to the return channel by the air-lift device and finally returned to the anaerobic zone. The sludge return ratio is strictly controlled at ≤100% to ensure that the granular sludge is evenly distributed in each functional zone, providing a guarantee for the stable cultivation of granular sludge.

[0013] Furthermore, in step S1, the carrousel oxidation ditch is divided into three independent functional zones by a partition wall: an anaerobic zone, a first micro-aeration zone, and a second micro-aeration zone. The first micro-aeration zone was transformed from the original I and II corridors of the Carrousel oxidation ditch; the second micro-aeration zone was transformed from the original III and IV corridors of the Carrousel oxidation ditch. Water passages are evenly distributed on the guide wall shared by corridors II and III to achieve orderly lateral flow. The circulation ditch of the Carrousel oxidation ditch is designated as an anaerobic zone. Low-speed flow mixers are installed in the anaerobic zone. The operating parameters of the low-speed flow mixers are based on avoiding damage to the granular sludge structure. This ensures that the sludge and wastewater are fully mixed, while preventing the granular sludge from being broken up, thus ensuring the stable progress of the reaction in the anaerobic zone.

[0014] Furthermore, in step S2, the adjustable bottom aeration system can precisely adjust the aeration rate to achieve controllable regulation of dissolved oxygen concentration. The dissolved oxygen concentration in the first micro-aeration zone is controlled at ≤0.5mg / L, and the dissolved oxygen concentration in the second micro-aeration zone is controlled at 0.3~1.0mg / L, so that a gradient of dissolved oxygen distribution is formed in the oxidation ditch. At the same time, bottom aeration can effectively prevent sludge from depositing at the bottom of the tank.

[0015] Furthermore, in step S3, the flow velocity of the sewage through the distribution pipe is 0.3~0.5m / s.

[0016] This invention also discloses a low-depth lateral flow aerobic granular sludge treatment device, comprising a carousel oxidation ditch, an anaerobic zone, and a microaerobic aeration zone; The anaerobic zone is located at the ends of the carousel oxidation ditch where the inlet and outlet are located, and the anaerobic zone is equipped with a low-speed propeller; a return channel is provided between the anaerobic zone and the aeration zone; The micro-aeration zone includes a first micro-aeration zone and a second micro-aeration zone; the first micro-aeration zone and the second micro-aeration zone are arranged parallel to each other in the micro-aeration zone; the first micro-aeration zone and the second micro-aeration zone are separated by a partition wall, and a water distribution channel is provided on the partition wall; the inlet is connected to the first micro-aeration zone, and the outlet is connected to the second micro-aeration zone; The second microaerobic aeration zone is equipped with an aerobic granular sludge generator.

[0017] The beneficial effects of this invention are as follows: 1. Aerobic granular sludge technology was implemented in low-depth water tanks. 2. Pollutant removal efficiency is significantly improved. By utilizing the existing corridors of the oxidation ditch, a zoned design and two-stage series connection are achieved. An adjustable blower bottom aeration system is used to create dissolved oxygen gradients of 0~0.5 mg / L and 0.5~1.0 mg / L, which creates aerobic, anoxic, and anaerobic microenvironments in the outer, middle, and inner layers of the granular sludge, respectively. This enables multiple reactions such as simultaneous nitrification and denitrification, short-cut nitrification and denitrification, denitrification for phosphorus removal, and aerobic excess phosphorus uptake, removing different types of pollutants in stages. The multi-stage series connection design effectively extends the effective retention time of wastewater in the system, further enhancing the pollutant degradation effect and significantly improving the removal efficiency of COD, nitrogen, and phosphorus.

[0018] 3. Shorten the granular sludge formation cycle and ensure the stability of granular sludge. By modifying the flow regime, optimizing the aeration layout, and incorporating an aerobic granular sludge generator, suitable hydraulic shear force, organic load, and growth environment are provided for granular sludge formation, promoting microbial self-flocculation to form a stable granular structure. The airlift reflux system replaces the traditional pump reflux, avoiding mechanical damage to the granular sludge from the pump body, while achieving uniform distribution of granular sludge in each functional area, ensuring the cultivation efficiency and stability of the granular sludge.

[0019] 4. Low retrofit cost and low energy consumption This invention is based on the original structure of the Carrousel oxidation ditch and is modified without the need for major reconstruction or expansion, which effectively reduces the cost of engineering modification. Compared with traditional surface aeration, the adjustable blower bottom aeration system has higher oxygen transfer efficiency and lower energy consumption. The air lift reflux system replaces the pump reflux, which further reduces the system's operating energy consumption and maintenance costs. At the same time, the modified process capacity is significantly improved, and no new tank is needed, which reduces the footprint. Attached Figure Description

[0020] Figure 1 Structural diagram of the invention; Among them: 1-Carrousel oxidation ditch body, 2-Anaerobic zone, 3-Microaerobic aeration zone, 4-Return channel, 21-Low-speed propeller, 31-First microaerobic aeration zone, 32-Second microaerobic aeration zone, 33-Partition wall, 321-Aerobic granular sludge generator, 331-Water distribution channel; Detailed Implementation

[0021] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical embodiments of the present invention, and should not be used to limit the scope of protection of the present invention.

[0022] Example 1 This invention discloses a method for converting a four-channel Carrousel oxidation ditch into a continuous flow aerobic granular sludge treatment, comprising the following steps: S1, Flow Modification Install partition walls within the Carrousel oxidation ditch to break the original circular flow pattern of the ditch and transform it into a lateral flow pattern; S2, Aeration System Modification The original inverted umbrella aeration or surface aeration methods have been abandoned and replaced with an adjustable blower bottom aeration system; S3, Water Distribution and Return System The water distribution and return system is built at the common wall of the Carrousel oxidation ditch I and II, and is equipped with a water distribution channel and a return channel. The water distribution channel is equipped with one or more rows of water distribution holes, or is replaced with water distribution pipes with small holes. Wastewater is evenly distributed to the entire tank through the water distribution pipes, avoiding sludge deposition caused by excessively low local water flow velocity and achieving uniform distribution of influent load. The return channel serves as a channel for sludge return, realizing the directional circulation of granular sludge from subsequent units to the anaerobic zone. S4. Construction of granular sludge cultivation system An aerobic granular sludge generator is built into the second microaerobic aeration zone. This generator has the dual functions of granular sludge cultivation and sludge-water separation, providing a suitable growth environment for microbial self-flocculation to form granular sludge. An air-lift device is connected to the sludge hopper of the aerobic granular sludge generator. The air-lift device is connected to the return channel, replacing the traditional pump return method. The sludge at the bottom of the generator is lifted to the return channel by the air-lift device and finally returned to the anaerobic zone. The sludge return ratio is strictly controlled at ≤100% to ensure that the granular sludge is evenly distributed in each functional zone, providing a guarantee for the stable cultivation of granular sludge.

[0023] In this embodiment, in step S1, the carousel oxidation ditch is divided into three independent functional zones by a partition wall: an anaerobic zone, a first micro-aerobic aeration zone, and a second micro-aerobic aeration zone. The first micro-aeration zone was transformed from the original I and II corridors of the Carrousel oxidation ditch; the second micro-aeration zone was transformed from the original III and IV corridors of the Carrousel oxidation ditch. Water passages are evenly distributed on the guide wall shared by corridors II and III to achieve orderly lateral flow. The circulation ditch of the Carrousel oxidation ditch is designated as an anaerobic zone. Low-speed flow mixers are installed in the anaerobic zone. The operating parameters of the low-speed flow mixers are based on avoiding damage to the granular sludge structure. This ensures that the sludge and wastewater are fully mixed, while preventing the granular sludge from being broken up, thus ensuring the stable progress of the reaction in the anaerobic zone.

[0024] In this embodiment, the adjustable bottom aeration system in step S2 can achieve controllable regulation of dissolved oxygen concentration by precisely adjusting the aeration rate. The dissolved oxygen concentration in the first micro-aeration zone is controlled at ≤0.5mg / L, and the dissolved oxygen concentration in the second micro-aeration zone is controlled at 0.3~1.0mg / L, so that a gradient of dissolved oxygen distribution is formed in the oxidation ditch. At the same time, bottom aeration can effectively prevent sludge from depositing at the bottom of the tank.

[0025] In this embodiment, during step S3, the flow velocity of the sewage through the distribution pipe is 0.3~0.5m / s.

[0026] This invention also discloses a low-depth lateral flow aerobic granular sludge treatment device, comprising a carousel oxidation ditch, an anaerobic zone, and a microaerobic aeration zone; The anaerobic zone is located at the ends of the carousel oxidation ditch where the inlet and outlet are located, and the anaerobic zone is equipped with a low-speed propeller; a return channel is provided between the anaerobic zone and the aeration zone; The micro-aeration zone includes a first micro-aeration zone and a second micro-aeration zone; the first micro-aeration zone and the second micro-aeration zone are arranged parallel to each other in the micro-aeration zone; the first micro-aeration zone and the second micro-aeration zone are separated by a partition wall, and a water distribution channel is provided on the partition wall; the inlet is connected to the first micro-aeration zone, and the outlet is connected to the second micro-aeration zone; The second microaerobic aeration zone is equipped with an aerobic granular sludge generator.

[0027] To further illustrate the beneficial effects of this application, data from before and after the renovation of the carousel oxidation ditch at a wastewater treatment plant are used as application examples and comparative examples, respectively.

[0028] Application Example 1 After the renovation, the quality of the effluent was significantly improved, energy and chemical consumption were significantly reduced, operation and maintenance efficiency was enhanced, and the effluent consistently met the quasi-IV standard (TN<15mg / L).

[0029] The parameters for aerobic granular sludge are as follows: Chi Shen 4~6m Particle size range 0.1~0.6mm MLSS (Mixed Lime Sludge Concentration) 5000~12000 mg / L Sludge Volume Index (SVI) 30~50mL / g SRT (Sludge Time) 10~30d DO (aerobic segment) ≤1.0mg / L reactor form Continuous flow After the modification, the effluent from the biological treatment system is as follows: COD: ≤35mg / L, average effluent COD 22mg / L; Ammonia nitrogen: ≤1.0 mg / L, average effluent concentration 0.3 mg / L; TN: ≤12mg / L, average effluent concentration 9.5mg / L; TP: ≤1.0mg / L, average effluent concentration 0.7mg / L; Phosphorus removal chemicals are reduced by 60%, carbon source by 100%, and electricity consumption by 30%. Comparative Example 1 Before the modification, the effluent from the biological treatment system was: COD: ≤50mg / L Ammonia nitrogen: ≤5.0 mg / L TN: ≤15mg / L TP: ≤2.5mg / L By comparing the above application example 1 and comparative example 1, it can be seen that the effect of the present invention is better than that of the traditional carousel oxidation ditch.

[0030] To further demonstrate that the configuration of this invention solves the problem of shallow application of aerobic granular sludge, the granular sludge data in Application Example 1 is compared with that of ordinary granular sludge as follows: Comparative Example 2 Chi Shen 6~8m 4~6m Common particle size range 1.0~2.0mm 0.1~0.6mm MLSS (Mixed Lime Sludge Concentration) 6000 ~ 10000 mg / L 5000~12000 mg / L Sludge Volume Index (SVI) 20~50 mL / g 30~50mL / g SRT (Sludge Time) 10 ~ 20 d 10~30d DO (aerobic segment) 2.0 ~ 4.0 mg / L ≤1.0mg / L reactor form Sequential batch Continuous flow By comparing the above application example 1 and comparative example 2, and considering the water purification effect of application example 1, it can be seen that the present invention solves the problem of applying aerobic granular sludge at shallow depths by configuring aerobic granular sludge parameters.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for converting a four-corridor carousel oxidation ditch into a continuous flow aerobic granular sludge treatment, characterized in that, Includes the following steps: S1, Flow Modification Install partition walls inside the Carrousel oxidation ditch to break the original circular flow pattern of the ditch and transform it into a lateral flow; S2, Aeration System Modification The original inverted umbrella aeration or surface aeration method has been abandoned and replaced with an adjustable blower bottom aeration system. S3, Water Distribution and Return System The water distribution and return system is built at the common wall of the Karusel oxidation ditch I and II, and is equipped with a water distribution channel and a return channel. The water distribution channel is equipped with one or more rows of water distribution holes, or is replaced with water distribution pipes with small holes. Wastewater is evenly distributed to the entire tank through the water distribution pipes, avoiding sludge deposition caused by excessively low local water flow velocity and achieving uniform distribution of influent load. The return channel serves as a channel for sludge return, realizing the directional circulation of granular sludge from subsequent units to the anaerobic zone. S4. Construction of granular sludge cultivation system An aerobic granular sludge generator is built into the second microaerobic aeration zone. This generator has the dual functions of granular sludge cultivation and sludge-water separation, providing a suitable growth environment for microbial self-flocculation to form granular sludge. An air-lift device is connected to the sludge hopper of the aerobic granular sludge generator. The air-lift device is connected to the return channel, replacing the traditional pump return method. The sludge at the bottom of the generator is lifted to the return channel by the air-lift device and finally returned to the anaerobic zone. The sludge return ratio is strictly controlled at ≤100% to ensure that the granular sludge is evenly distributed in each functional zone, providing a guarantee for the stable cultivation of granular sludge.

2. The method for converting a four-corridor carousel oxidation ditch into a continuous flow aerobic granular sludge as described in claim 1, characterized in that, In step S1, the carousel oxidation ditch is divided into three independent functional zones by a partition wall: an anaerobic zone, a first micro-aeration zone, and a second micro-aeration zone. The first micro-aerobic aeration zone was transformed from the original I and II corridors of the Carrousel oxidation ditch; the second micro-aerobic aeration zone was transformed from the original III and IV corridors of the Carrousel oxidation ditch. Water passages are evenly distributed on the guide wall shared by corridors II and III to achieve orderly lateral flow. The circulation ditch of the Carrousel oxidation ditch is designated as an anaerobic zone. Low-speed flow mixers are installed in the anaerobic zone. The operating parameters of the low-speed flow mixers are based on avoiding damage to the granular sludge structure. This ensures that the sludge and wastewater are fully mixed, while preventing the granular sludge from being broken up, thus ensuring the stable progress of the reaction in the anaerobic zone.

3. The method for converting a four-corridor carousel oxidation ditch into a continuous flow aerobic granular sludge as described in claim 1, characterized in that, In step S2, the adjustable bottom aeration system can precisely adjust the aeration volume to achieve controllable regulation of dissolved oxygen concentration. The dissolved oxygen concentration in the first micro-aeration zone is controlled at ≤0.5mg / L, and the dissolved oxygen concentration in the second micro-aeration zone is controlled at 0.3~1.0mg / L, so that a gradient of dissolved oxygen distribution is formed in the oxidation ditch. At the same time, bottom aeration can effectively prevent sludge from depositing at the bottom of the tank.

4. The method for converting a four-corridor carousel oxidation ditch into a continuous flow aerobic granular sludge as described in claim 1, characterized in that, In step S3, the flow velocity of the sewage through the distribution pipe is 0.3~0.5m / s.

5. A low-depth lateral flow aerobic granular sludge treatment device, characterized in that, This includes the Carrousel oxidation ditch body, anaerobic zone, and microaerobic aeration zone; The anaerobic zone is located at the end of the inlet and outlet of the Carrousel oxidation ditch, and the anaerobic zone is equipped with a low-speed propeller; a return channel is provided between the anaerobic zone and the aeration zone. The micro-aeration zone includes a first micro-aeration zone and a second micro-aeration zone; the first micro-aeration zone and the second micro-aeration zone are arranged in parallel in the micro-aeration zone; the first micro-aeration zone and the second micro-aeration zone are separated by a partition wall, and a water distribution channel is provided on the partition wall; the inlet is connected to the first micro-aeration zone, and the outlet is connected to the second micro-aeration zone. The second microaerobic aeration zone is equipped with an aerobic granular sludge generator.

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